Work vehicles are known to carry heavy loads, and often to carry these loads over unpaved surfaces such as dirt roads and around construction sites. In particular, cement trucks carry large drums full of cement long distances and often must traverse unpaved surfaces to access the site for unloading the cement from the drum. Cement trucks typically include a cab for the operator and a rotatable drum behind the cab for containing and mixing concrete. Such cement trucks further typically include a set of front wheels for steering, and plural rear drive axles carrying dual wheel arrangements mounted on a continuous elongate chassis for load-support. For additional load-support, particularly in-transit when the drum is substantially full, a cement truck can benefit by having a pivotally mounted tag axle (auxiliary axle) system able to operate between a raised position in which it is carried by the truck, and a lowered/deployed position in which the tag axle and its wheels share the truck's load.
Not only does the tag axle system assist in balancing the load carried by the cement truck when the drum is fully loaded, it may enable the cement truck to carry a higher total payload than would otherwise be permitted, because weight restrictions placed on vehicles traveling over highways are typically measured in terms of load per axle in combination with overall spacing between axles of a vehicle. By deploying a tag axle system, the number of axles as well as the spacing thereof can be temporarily increased when the truck is heavily loaded, thereby enabling the truck to transport a higher total legal payload.
It is known to have tag axle systems generally consisting of a rear tubular cross member welded to the truck frame, and two tag axle arms pivotally mounted to and extending rearwardly from the tubular cross member. According to a known arrangement, pins are inserted into the ends of the cross member and through apertures in the arms to hold the tag axle arms in place on the cross member with the aid of a set screw. Bearings surround the pin to allow smooth pivoting of the arms. This design is problematic in that over a period of a few years, the bearings may fail and seize to the pin, and the pin may seize to the ends of the cross member. Since cement trucks are often washed with an acid/water solution to remove cement particles from the truck surface, the acid/water solution may come into contact with the tag axle system components and accelerate corrosion of the components, thereby accelerating seizure of those components. Additionally, since load-hauling vehicles are often driven over unpaved surfaces, movement and twisting of the tag axle system components may occur and cause cross member flexure and articulation of the components. As a result of use, and seizing and articulation of the components, over time it becomes more difficult to disassemble and maintain the system, except by cutting the failed components from the frame (typically with a torch) and replacing them. Such permanently mounted components may limit the use of the vehicle (as the frame is itself modified).
Accordingly, it would be advantageous to provide a tag axle system which is relatively simple and inexpensive to produce, and which allows simplified disassembly of the tag axle system for maintenance such as replacement of corroded, seized components of the system.